G6 Florence B. Sabin. 



Prom the jugular lymph sac in the pig it is clear in fig. 16 t 

 two lymph glands develop: (1) the deep jugular lymph node wh 

 drains the pharynx and (2) the node in the posterior triangle of 

 neck which drains the skin of the anterior part of the body. A. 

 Clark (24) has shown that these two glands are single glands in 

 neck of the adult pig and that they become the largest of all the cervi 

 glands. In the human embryo these two glands are represented 

 groups of glands, the glands of the posterior triangle and the d 

 jugular glands. In the human embryo also the group of deep axil! 

 glands comes from an extension of the jugular sac along the primit 

 ulnar vein and hence they are primary lymph glands. Thus the j 

 mary nodes for the anterior part of the body are (1) deep jugular noc 



(2) the nodes of the posterior triangle, (3) the axillary nodes. T 

 relation of the primary lymph gland, both to the various structu 

 of the neck and to the stalk of the jugular sac, that is, to the jugu 

 lymph trunks, is shown especially well in fig. 17 from pig 7.5 c 

 long. The anterior curvature and the sac stalk lie behind, that 

 medial to the sternocleidomastoid muscle. Of the primary nodes 

 the neck the deep jugular nodes drain a restricted area, namely, 

 pharynx and nose; the axillary lymph nodes drain the arm, and 

 large node of the posterior triangle drains all the rest of the head, fa 

 neck a,nd thorax, either directly or through the superficial cervi 

 plexus. The nodes of the superficial cervical plexus are secondary 

 the primary lymph sac nodes. It has been brought out that th 

 groups of lymphatics do not remain distinct as they arise, but all 

 come connected with each other through anastomoses of the lym 

 vessels. 



Prom the retroperitoneal sac develop the retroperitoneal lym 

 nodes. Prom the iliac sacs in the pig there is a chain of small rro< 

 lateral to the aorta and a large group of glands on either side oppos 

 the bifurcation of the aorta. These are primary iliac nodes. Dor 

 to the aorta is a chain of nodes from the lower end of the ciste: 

 chjili to the bifurcation ef the aorta. Thus the renal lymphatics g 

 rise to three groups of primary lymphatic glands: (1) prse-aortic 

 retroperitoneal, (2) symmetrical iliac nodes lateral to the aorta, t 



(3) prse-vertebral nodes dorsal to the aorta. 



The secondary lymphatic nodes develop along the lymphatic- vessi 

 The most extensive group of secondary nodes in the embryo pig is 

 one which comes from the superficial cervical plexus along the exter 



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